1. Field of the Invention
The present invention relates to a shock absorber for a two-wheeled vehicle. In particular, the present invention relates to a shock absorber for a two-wheeled vehicle for effectively protecting an occupant against a frontal crash of the two-wheeled vehicle.
2. Description of Background Art
A shock absorber is used in an automotive vehicle for protecting occupants in case of a collision. For example, shock absorbers are provided inside of pillar garnishes for protecting the heads of the occupants and inside of the door trims for protecting the backs or the chests of the occupants and the like in case of a side collision. Resin ribs that can be manufactured at relatively low cost have been in heavy usage as shock absorbers (See JP-A-8-164810, JP Patent No.2978083, etc.).
However, with regard to two-wheeled vehicles, the absorption of energy in case of a collision has not been examined so far.
A shock absorber for a two-wheeled vehicle is required to absorb a much larger amount of energy in comparison with that for an automotive vehicle. For example, in the case of an automotive vehicle, kinetic energy to be absorbed Ek=xc2xd mv2 is 102.1 [J], which is determined based on the energy generated when a dummy head of 4.54 kg in mass clashes at a speed of 15 mile/h (=6.71 m/s). In the case of a two-wheeled vehicle, kinetic energy to be absorbed Ek is 9646 [J], where the vehicle mass is 100 kg, and the traveling velocity is 50 km/h (=13.89 m/s). Accordingly, an incommensurably large energy absorption must be realized.
Assuming that a resin rib for an automotive vehicle is used, the height of the rib is in the order of 60 mm at most. Accordingly, a considerably large area is required on the two-wheeled vehicle when the resin rib, having the same absorption stroke, is applied thereto, which is actually impossible. The shock absorber is to be mounted at the front end of the two-wheeled vehicle. Accordingly, it is impossible to enlarge the front area thereof. On the other hand, assuming that a method of increasing the height of the resin rib is employed, the rib may be ever-increasingly thicker because it is necessary to provide a draft angle for manufacturing reasons. This results in a disadvantage in that a generated load increases.
In order to solve the aforementioned problems, it is an object of the present invention to provide a shock absorber for a two-wheeled vehicle that effectively absorbs a large energy generated in case of a collision and that may be easily mounted on a two-wheeled vehicle.
In order to achieve the aforementioned object, according to a first aspect of the present invention, a shock absorber for a two-wheeled vehicle includes shock absorbing members of synthetic resin. Each of the shock absorbing members comprise a lattice body including a plurality of plate ribs reduced in thickness from the proximal ends toward the distal ends and being disposed intersecting with each other. The lattice bodies are arranged in a stack in such a manner that the direction of the plate ribs extending from the proximal ends toward the distal ends is oriented along the fore-and-aft direction of the two-wheeled vehicle. The lattice bodies are mounted at the front end of the two-wheeled vehicle.
According to a second aspect of the present invention, a shock absorber for a two-wheeled vehicle includes shock absorbing members of synthetic resin. Each of the shock absorbing members comprises a lattice body including a plurality of plate ribs reduced in thickness from the proximal ends toward the distal ends and disposed intersecting with each other. A tabular basal plate is provided for shielding each lattice space of the lattice body molded integrally with each other. The lattice bodies are arranged in a stack in such a manner that the direction of the plate ribs extending from the proximal ends toward the distal ends is oriented along the fore-and-aft direction of the two-wheeled vehicle. The lattice bodies are mounted at the front end of the two-wheeled vehicle.
The shock absorber for a two-wheeled vehicle according to a third aspect of the present invention includes the lattice opening at the center of the lattice body being made larger than the lattice openings formed on the portion other than the center.
The shock absorber for a two-wheeled vehicle according to a fourth aspect of the present invention includes a part of the plate ribs positioned in the central area of the lattice body being thinned out when forming the lattice body by disposing a plurality of plate ribs intersecting with each other.
According to the first aspect of the present invention, the lattice bodies are arranged in a stack in such a manner that the direction of the plate ribs extending from the proximal end toward the distal end is oriented along the fore-and-aft direction of the two-wheeled vehicle. The lattice bodies are mounted at the front end of the two-wheeled vehicle. Arranging the lattice bodies in a stack (stacking lattice bodies) contributes to secure a large shock absorbing stroke for a frontal collision of the two-wheel vehicle, thereby a large impact to be absorbed as desired. In addition, since the shock absorbing members are arranged in a stack, the height of the plate rib in the lattice body, which constitutes each tier, may be reduced to the value in the order of 60 mm, so that the proximal end of the rib is prevented from being too thick even when a draft angle is provided, and thus such disadvantage that the generated load increases may not arise.
According to the second aspect of the present invention, the shock absorbing members including the lattice body and the basal plate molded integrally with each other are arranged in a stack. In the case where each of the shock absorbing members arranged in a stack is subjected to an impact load, the basal plate receives the impact load as a whole in a first place. The impact load is then transmitted to each plate rib, and the plate ribs are crushed continuously to absorb the impact load effectively.
According to the third and fourth aspects of the present invention, the lattice opening at the center of the lattice body is made larger than the lattice openings formed on the portion other than the center. Alternatively, a part of the plate ribs positioned in the central area of the lattice body is thinned out in forming a lattice body by disposing a plurality of plate ribs intersecting with each other. The strength of the shock absorber formed by arranging the shock absorbing members in a stack is low at the portion near the central axis in comparison with the cases in which all the openings are the same in size as a whole, and in which thinning-out is not made, and thus it crushes stably when being subjected to an impact load.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.